Method for making lithium-sulfur battery separator

Abstract

The present disclosure relates to a method for making a lithium-sulfur battery separator. The method comprises providing a separator substrate, and forming a functional layer on at least one surface of the separator substrate. A method for forming the functional layer comprises applying a first carbon nanotube layer on the at least one surface; dispersing a plurality of graphene oxide sheets and a plurality of manganese dioxide nanoparticles in a solvent to form a mixture; and depositing the mixture on a surface of the first carbon nanotube layer to form a first graphene oxide composite layer; applying a second carbon nanotube layer on a surface of the first graphene oxide composite layer; and forming a second graphene oxide composite layer on a surface of the second carbon nanotube layer.

What is claimed is: 
     
       1. A method for making a lithium-sulfur battery separator comprising
 step (S 1 ), providing a separator substrate comprising a first surface and a second surface opposite to the first surface; and 
 step (S 2 ), forming a functional layer on at least one surface of the first surface and the second surface, and a method for forming the functional layer on at least one surface of the first surface and the second surface comprises sub-steps of: 
 step (S 21 ), applying a first carbon nanotube layer on the at least one surface of the first surface and the second surface; 
 step (S 22 ), providing a plurality of graphene oxide sheets and a plurality of manganese dioxide nanoparticles; dispersing the plurality of graphene oxide sheets and the plurality of manganese dioxide nanoparticles in a solvent to form a mixture; and depositing the mixture on a surface of the first carbon nanotube layer to form a first graphene oxide composite layer; 
 step (S 23 ), applying a second carbon nanotube layer on a surface of the first graphene oxide composite layer; and 
 step (S 24 ), forming a second graphene oxide composite layer on a surface of the second carbon nanotube layer. 
 
     
     
       2. The method of  claim 1 , wherein the first carbon nanotube layer comprises at least two carbon nanotube films stacked and crossed with each other. 
     
     
       3. The method of  claim 2 , wherein the first carbon nanotube layer comprises two carbon nanotube films stacked and crossed with each other, and a method of applying the first carbon nanotube layer on the at least one surface of the first surface and the second surface comprises the following steps:
 laying a first carbon nanotube film on the at least one surface of the first surface and the second surface; and 
 laying a second carbon nanotube film on a surface of the first carbon nanotube film, wherein a first extending direction of the carbon nanotubes in the first carbon nanotube film intersects with a second extending direction of the carbon nanotubes in the second carbon nanotube film. 
 
     
     
       4. The method of  claim 2 , wherein the first carbon nanotube layer comprises more than two carbon nanotube films stacked and crossed with each other, and a method of applying the first carbon nanotube layer on the at least one surface of the first surface and the second surface comprises the following steps:
 step (S 211 ), laying a first carbon nanotube film on the at least one surface of the first surface and the second surface; 
 step (S 212 ), laying a second carbon nanotube film on a surface of the first carbon nanotube film, wherein a first extending direction of the carbon nanotubes in the first carbon nanotube film intersects with a second extending direction of the carbon nanotubes in the second carbon nanotube film; 
 step (S 213 ), laying a third carbon nanotube film on a surface of the second carbon nanotube film, wherein a third extending direction of the carbon nanotubes in the third carbon nanotube film intersects with the second extending direction of the carbon nanotubes in the second carbon nanotube film; and 
 step (S 214 ), repeating step (S 212 ) and step (S 213 ) until the first carbon nanotube layer is obtained. 
 
     
     
       5. The method of  claim 1 , wherein the first carbon nanotube layer is directly laid on the separator substrate after drawn from a carbon nanotube array. 
     
     
       6. The method of  claim 1 , wherein in step (S 21 ), further comprising fixing the separator substrate to a planar glass before applying the first carbon nanotube layer on the at least one surface of the first surface and the second surface. 
     
     
       7. The method of  claim 1 , wherein in step (S 22 ), the plurality of graphene oxide sheets and the plurality of manganese dioxide nanoparticles are uniformly dispersed in the solvent by a mechanical stirring. 
     
     
       8. The method of  claim 1 , wherein in step (S 22 ), the plurality of graphene oxide sheets and the plurality of manganese dioxide nanoparticles are uniformly dispersed in the solvent by an ultrasonic shock. 
     
     
       9. The method of  claim 1 , wherein a weight ratio between the plurality of manganese dioxide nanoparticles and the plurality of graphene oxide sheets is ranged from about 1:2 to about 1:1. 
     
     
       10. The method of  claim 1 , wherein a method of depositing the mixture on the surface of the first carbon nanotube layer comprises the following steps: the mixture is uniformly deposited on the surface of the first carbon nanotube layer; the first carbon nanotube layer is impregnated by the mixture; and the solvent in the mixture is removed by heating. 
     
     
       11. The method of  claim 10 , wherein the mixture is uniformly deposited on the surface of the first carbon nanotube layer by a dropper. 
     
     
       12. The method of  claim 10 , wherein the mixture is uniformly deposited on the surface of the first carbon nanotube layer by a slow dumping. 
     
     
       13. The method of  claim 1 , wherein step (S 23 ) and step (S 24 ) are repeated seven times to eleven times. 
     
     
       14. The method of  claim 1 , wherein a diameter of each of the plurality of manganese dioxide nanoparticles is ranged from about 5 nanometers to about 10 nanometers. 
     
     
       15. The method of  claim 1 , wherein a thickness of the functional layer is ranged from about 1 micrometer to about 3 micrometers.